Charles Darwin visited the Galapagos on HMS Beagle in 1835 and collected a dozen species of finch that he realised had evolved from a bird on the South American mainland. Since then, they have diversified in the same way that the Big Birds did, and resulted in different species with different beak sizes and features, allowing them to utilize the different food sources with the other species. According to Science Daily, the male bird was a large cactus finch. They tracked this lineage - which they dubbed the "Big Bird" lineage - for six generations, regularly taking blood samples for use in genetic analysis.
Nearly 40 years ago, a graduate student working with the researchers noticed a male bird that was much larger in body and beak size than the species that were known natives on Daphne Major.
Blood and DNA samples enabled researchers to discover that the unusual new bird was actually a large cactus finch of the species Geospiza conirostris from Española island, more than 100 km (62.14 miles) away from Daphne Major. Prior, the theory primarily relied on fossil records and species hybridisation, though an existing species had never been observed evolving into an entirely new species.
"The novelty of this study is that we can follow the emergence of new species in the wild", said B. Rosemary Grant, a senior research biologist, emeritus, and a senior biologist in the Department of Ecology and Evolutionary Biology. Instead, he settled on one of the three finch species on the island.
Interbreeding between the two different species of finches produced fertile offspring of a new species.
Not content to live out his life on the island where he clearly didn't belong, he actually managed to find a mate among the native finch species, resulting in hybridized offspring that were a mix of the two. Unlike their father, the male offspring were unable to attract females from other species due to the fact that their song was especially unusual and their beaks were odd sizes and shapes.
It is assumed that the process of evolution and the creation of new species take a long time but in the case of the Big Birds, researchers found that the new species was created just after two generations.
"We have no indication about the long-term survival of the Big Bird lineage, but it has the potential to become a success, and it provides a handsome example of one way in which speciation occurs", said Leif Andersson, a professor at Uppsala University.